Add demo on period finding

[mariaschuld]

Title:

Period finding -- a problem at the heard of quantum computing

We could use a less bulky title

Summary:

Introduces hidden subgroup problems, using a simple example.

• GOALS — Why are we working on this now?

Basis for the theory we're crafting in the QML team. Good basic quantum computing content to share.

• AUDIENCE — Who is this for?

Quantum computing researchers in general

• KEYWORDS — What words should be included in the marketing post?

Hidden subgroup problem, period finding, Shor's algorithm, Abelian groups, Quantum Fourier Transform

• Which of the following types of documentation is most similar to your file?
  (more details here)

• Tutorial
• [ X] Demo
• How-to

[sc-81652]

[github-actions]

👋 Hey, looks like you've updated some demos!

🐘 Don't forget to update the dateOfLastModification in the associated metadata files so your changes are reflected in Glass Onion (search and recommendations).

Please hide this comment once the field(s) are updated. Thanks!

[mariaschuld]

@alvaro-at-xanadu, it would be great if you'd have a quick look at why the build is failing...your experience might save us a lot of time guessing what's wrong with the metadata :)

PS: I failed to run the json file check locally, because I didn't know what to put for <largest_number> in /demo.metadata.schema.<largest_number>.json...maybe I missed it somewhere

[github-actions]

Thank you for opening this pull request.

You can find the built site at this link.

Deployment Info:

• Pull Request ID: 1324
• Deployment SHA: fd31628f6f632a573cc16bbba523339cc3eb6350
  (The Deployment SHA refers to the latest commit hash the docs were built from)

Note: It may take several minutes for updates to this pull request to be reflected on the deployed site.

[CatalinaAlbornoz]

I'm testing the titles to see if this was causing the issue

[CatalinaAlbornoz]

I changed the number of hashes in the penultimate section and removed the hashes before the references title

[mariaschuld]

Just minor copy things, and then we're ready to go! @mariaschuld I marked it as approved, but please do take a look at the minor copy-edits and commit if you agree :)

Thanks @alvaro-at-xanadu. I found one more rendering issue marked in the comments, but accepted all of your suggestions.

[cognigami]

Will remove hero image before posting. Otherwise, LGTM.

[justinpickering]

Looks great! Just a couple comments before we release (aiming for tomorrow, Apr 16).
cc @cognigami

[justinpickering]

Just want to confirm this is a 'Getting Started' category demo? Typically these are 'how to' demos and less advanced topics.

Here are other Categories we can choose from. Any others that apply (can have multiple).